The latest redundancies will cut VSEL's workforce to just 6,000, compared with 14,000 four years ago, and were accompanied by a warning of yet more job losses.
A spokesman said earlier predictions that the number of workers would fall to 5,000 eventually were still expected to be accurate.
The remaining workforce will continue working on the three Trident submarines still to be completed and an order for the AS90 self-propelled gun for the British Army.
Ray Davies, the personnel director, said: 'We regret very much having to make today's announcement, but I think that people now appreciate that we have no alternative other than to respond to our reducing workload if we are to remain competitive and secure our long- term future.'
The job cuts will be spread among blue and white-collar workers. A further review of jobs would take place in the shipbuilding division and an announcement would be made when that was complete, the company added. VSEL said it was seeking as many volunteers for redundancy as possible.
The first Trident submarine has been completed. The second, Victorious, is almost ready for sea trials. Work on the third and fourth vessels is under way.
The latest job losses were not unexpected as VSEL had been warning of further cuts. The company warned last October that it might eventually have to slim down the workforce to 5,000 because of cuts in defence spending.
Alex Ferry, general secretary of the Confederation of Shipbuilding and Engineering Unions, said it highlighted the need for government help for defence-related companies to diversify into other areas of production.
'It is difficult to argue with the management to retain people when there is no work,' he said. 'We need a diversification policy in this country to help companies totally dependent on the defence sector to get into other markets.'
The 500 redundancies will add about 2 per cent to the area's unemployment rate, Mr Ferry estimated.